He deserves a lot of credit for working out a visually pleasing way to mount each component. There wasn’t any type of substrate used, but a few lower gauge wires were picked as the rails and they add some mounting stability. Before casting, he took the case of each of the three jacks apart and sealed the seams with some of the casting resin to prevent the final pour from filling them up.

Eagle CAD was used to design the mold. He printed it out on some card stock, then used a hobby knife to cut the pieces out and super glue to assemble them. A second layer of super glue was run on each seam to ensure they’re water tight. After the casting was made [Rupert] spent plenty of time sanding, routing, and polishing the brick to achieve this look.

This makes us wonder about heat dissipation. Do you think it will be a problem? Tells us what your opinion by leaving a comment.

60 thoughts on “Free formed circuit protected by a brick of crystal clear resin”

Actually here’s a thought toward improving the process somewhat; put all electromechanical parts on an endcap piece that connects to via a header block. Not quite as cool but would be less hassle and would make it possible to use pots/switches/other jacks.

Heat dissipation ? There is nothing there that will get hot – and actually the resin conducts heat quite good! It looks really cool, but there is absolutely no shielding, so bringing a cellphone close is not so smart…

It’s an amp. All amps need to get hot are electrons and a little bit of resistance in the wire.

A classic cMoy has a peak current of about 40mA and a 9v battery. Combine those to get power, and you have about 360mW, or about a third of a Watt.

A third of a Watt is about 1300 Joules per hour, or 22 Joules per minute. 1 Joule is enough energy to heat 1cc of water 1 degree C, so at most, this amp could channel enough power to heat 22cc of water at a rate of 1 degree C per minute.

I doubt that would be a problem, but the parts that could potentially get hot are buried deep, and resin is a good insulator. Any heat will stay close to the components that generate it. While that might not cause component failure, it will cause the resin at the center of the block to expand, with a possible risk of causing the plastic to crack.

My suggestion is to measure the temperature with an IR thermometer, run the thing at full power, and measure it at 1 minute, 5 minutes, 10 minutes, 30 minutes, and 1 hour (assuming you don’t see any alarming readings). Keep taking readings until you see the curve flatten out, at which point you’ll know that it’s reached a point where it dissipates heat as fast as the amp generates it.

You may see nothing.. if so, enjoy, and props for a beautiful build. If you do see a rise in heat that causes you concern, dial back the power until you get a curve that looks comfortable.

“The large calorie, kilogram calorie, dietary calorie, or food calorie (symbol: Cal) [2]->(http://www.merriam-webster.com/dictionary/calorie) approximates the energy needed to increase the temperature of 1 kilogram of water by 1 °C. This is exactly 1,000 small calories or about 4.2 kilojoules. It is also called the nutritionist’s calorie.” source: Wikipedia.

I did read the description, and was answering it. There is no heat concerns if the project made it past the exceptionally high temperature resin curing. I guess you decided not to read the description and posted like a jackass.

I love the look, and would like to do it on my preamps, but I would never do an unshielded build.

As an example.. I have an old Creek Audio 4140 integrated amp. The case is wood, and unshielded. Though the PCB might have a ground plane (which helps).

Every once in a while a trucker would drive by with an apparently really powerful CB and it would blast through my stereo completely unattenuated (max volume). It would really wake you up when you were dozing on the couch at 2AM (“hey good buddy, wake up and get off the couch!”).

From these (and earlier) pictures it looks like a fairly simple CMOY amplifier or a close relative, albeit wall rather than battery powered. CMOYs generally don’t churn out anywhere near enough juice to create much in the way of heat. The encasement could be a problem for highly current biased class A headphones amps, though.

Or almost any kind of speaker amp, really.

Anyway, it’s an awesome and well executed idea, so props to the creator.

I am impressed.
That’s actually not happening too often, not even here, but this is a wonderful example how you can fit a project into a package. The idea is simple, so simple in fact that I could have had it. And while I have sunk circuits in epoxy before for practical reasons and have built free wiring stuff, I never thought of doing it in this aesthetically pleasing way.

only problem: if any part fails you have to build a new unit so you may want to add extra protection such as a diode in series with the power connector and the amplifier chip so you dont blow it or the capacitors by reversing the power wires if you should ever have to replace the power supply with one of them universal power supply you can get at any electronics shop.

if the unit takes has a max of less than 12 volts you may want to use a voltage regulator to prevent over volting it if you should use the wrong setting on the universal power supplies.

most universal power supplies are a wall wart with a voltage selector that goes in 1.5 or 3 volt increments and are rated for up to1 amp and polarity can be set by a selector switch on the unit or reversing the plug tips.

they also make and sell universal power supplies for use in the car they plug into the lighter socket and work the same way.

You could clamp this thing into a CNC machine and engrave the resin with some neat patterns – If you had included a bright RGB LED in there the engraved patterns would internally reflect and make some awesome colour light show that could react to the frequencies passing through the opamp!

so what if something starts overheating? drill some holes near the problem components and pump cool water through. acrylic blocks always seemed cool to me, as in, a good thermal conductor.. but my cold cathode tubes, not so much. i’m not googling or wikiped’ing to correct a mistake before i make it, but i’m guessing the tubes are made with cyanoacrylate somehow, because hitting them with a torch made them expand strangely, releasing the stench of superglue.

Some shrink/grow when curing. All get hot so take note of temperatures. Some components like generic electrolytic caps (vent), resonators (mechanical interference), LEDs (chemical)etc. can not be encapsulated.

Regarding heat, most encapsulants are made to dissipate heat. Standard A/B epoxy resins are not and work quite well to insulate heat sources.

That’s a beautiful build.
I’m of the opinion that the more electronics encased in resin the better.
I’d love to see a build where someone encases an entire motherboard in resin and just has heatsinks poking out through it.
All media players should have resin, at least around the headphone jacks so they stop breaking.